Process diagram: Hydroelectric power generation

The diagram illustrates how electricity is generated at a hydroelectric power station, and it consists of eight stages.

Overall, the process converts the energy of falling water into electricity, which is then sent to consumers. The water is not consumed, since it is released back into the river at the end. The first four stages concern the movement of water, the next three concern electricity, and the last returns the water to the river.

The process begins at the dam, where a river is blocked to create a reservoir that stores water. The water then enters pipes called penstocks at the intake. Gravity drives it down the pipes towards the turbine, and the force of the water causes the turbine blades to rotate.

The spinning turbine drives a generator, which produces the electricity. Subsequently, the voltage is increased by a transformer so that the electricity can be transmitted over long distances.

At the final stages, the electricity is sent along power lines to homes and factories. At the same time, the water leaves the power station and is released to rejoin the river.